This invention is directed to apparatus and methodology for rounding the bristle tips of twisted wire brushes.
Twisted wire brushes are used in a variety of applications, particularly in personal care products. These brushes consist of a multiplicity of fine synthetic bristles held and secured by a pair of twisted metal wires which form the core of the brush. The bristles extend in various directions from the twisted wires and the overall brush has a cylindrical or a tapered cylindrical outer surface. The bristles are generally formed by thin nylon or plastic filaments. Because the bristle tips are cut, the ends of the bristles are quite sharp and can cause injury if inserted in the eye. This is a particular problem when the twisted wire brush is used as a mascara brush, which is a common application. Hollow bristle filaments have recently come into use since they are quite flexible and provide a uniform cylindrical appearance to the brush. However, the tips of these filaments are even sharper than solid filament bristles with a consequent increased possibility of injury.
A variety of processes have been proposed for rounding the bristle tips of various types of brushes. Such processes have included bringing the bristle tips into contact with a heated surface. Non-contact processes have included the use of heat lamps or laser beams acting on the bristle tips to melt same. However, these processes have generally been applicable only to brushes in which all of the bristles are oriented in the same direction, such as hair brushes. Such processes are unsatisfactory for use with brushes having a cylindrical outer surface such as twisted wire brushes.